DVDs become common as optical discs onto which various information such as main-video information, audio information, sub-video information, reproduction control information and so on is recorded. According to a DVD standard, the main-video information (video data), the audio information (audio data) and the sub-video information (sub-picture data) are packetized each with the reproduction control information (navigation data) and multi-recorded onto a disc in a program stream format of MPEG 2 (Moving Picture Experts Group phase 2), which is a high performance encoding technology. Among them, the main-video information has data, which is compressed in a MPEG video format (ISO 13818-2), for one stream in one program stream. On the other hand, the audio information is recorded in a plurality of formats (i.e. linear PCM, AC-3, MPEG audio and so on) and has data for up to 8 streams in one program stream. The sub-video information is defined by a bitmap, and is compressed and recorded in a run length method, and has data for up to 32 streams in one program stream.
On the other hand, a transport stream of MPEG2 standard is coming to be standardized, which is suitable for data transfer. According to the transport stream format, a plurality of elementary streams is transferred at the same time. For example, a plurality of programs, such as a plurality of satellite digital broadcasting channels in one satellite radio wave, is transmitted at the same time in a TDM (Time Division Multiplex) scheme.
In DVD's of this type, sub-picture information may be recorded as the sub-video information, such as a caption for a movie, in association with video information as the main-video information. Moreover, for example, it is possible to superimpose and display the pictures of various buttons, such as a button for menu selection and a button for operation execution, over the main-video.